I. Field of the Invention
The invention relates to improved asphalt compositions containing i) a solvent precipitated asphaltene component, e.g., solvent-deasphalted bottoms and ii) a viscosity reducing amount of paraffinic fluxing component added to improve rheological properties. The invention further relates to such improved asphalt compositions useful in a variety of applications, particularly paving asphalts where the reduced smoking characteristics of the compositions during paving are especially beneficial.
II. Description of the Prior Art
Solvent deasphalting (extraction of asphalts from heavy petroleum stocks) is a well-known petroleum process and is described in U.S. Pat. No. 3,951,781 to Owen (Mobil); U.S. Pat. No. 3,968,023 to Yan (Mobil); U.S. Pat. No. 3,972,807 to Uitti (UOP); U.S. Pat. No. 3,975,396 to Bushnell (Exxon); U.S. Pat. No. 3,981,797 to Kellar (UOP); U.S. Pat. No. 3,998,726 to Bunas (UOP); U.S. Pat. No. 4,017,383 to Beavon (Ralph M. Parsons); U.S. Pat. No. 4,054,512 to Dugan (Exxon); U.S. Pat. No. 4,101,415 to Crowley (Phillips); U.S. Pat. No. 4,125,458 to Bushnell (Exxon); and numerous others. Specific proprietary processes include the SOLVAHL solvent deasphalting process licensed by Institute Francais de Petrole, and the low-energy deasphalting process licensed by Foster Wheeler, U.S.A. Deasphalting processes also include the supercritical fluid technology licensed by Kerr-McGee Corporation.
U.S. Pat. No. 5,601,697 to Miller et al. teaches SDA-produced asphalts (containing solvent deasphalting bottoms) made by blending SDA bottoms with aromatic extract. Preferably the extract is produced from an extraction process such as that employed in lubricating oil production. The blending process produces asphalts of superior characteristics, e.g., PG64-22, which can meet the new Strategic Highway Research Program (SHRP) specifications for dynamic sheer, creep stiffness, and direct tension (tensile strength). As the new SHRP asphalt specifications impact the marketplace, particularly aided by the recent increases in federal funds for highway construction and repair, these new asphalt products will be particularly advantageous.
U.S. Pat. No. 3,607,334 to Fauber discloses an asphaltic composition used as felt saturants or roofing materials comprising a major amount of asphalt and a minor amount of a second pass foots oil derived from heavy lube distillate.
U.S. Pat. No. 3,920,467 to Stewart, et al. discloses an asphalt composition of enhanced durability. The composition comprises solvent deasphalting (SDA) bottoms unmodified or modified, e.g., by treatment with phenyl isocyanate. A minor amount of paraffinic foots oil (34 wt. %) is subsequently added to the unmodified or modified SDA bottoms in order to adjust the penentration of the samples.
U.S. Pat. No. 3,663,281 to Fauber, discloses asphaltic compositions suited for use in paper laminates which are prepared by airblowing a blend of a major amount of asphalt and a minor amount of foots oil derived from slack wax from a medium lubricating oil distillate.
U.S. Pat. No. 4,499,187 to Blackburn, et al., discloses a method for evaluating carcinogenic activity of hydrocarbons by biological assay. Low carcinogenic activity for solvent refined/dewaxed residual oil and solvent refined/hydrotreated heavy paraffinic distillate is shown in Table II. The reference neither discloses nor suggests the incorporation of such materials in asphalt paving compositions.
U.S. Pat. No. 5,308,470 to Blackburn, et al., discloses asphalt compositions comprising asphalt blending stocks prepared by the distillation of deasphalted oils, or bright stock extracts (aromatic extracts) into specific IBP and 5% Overhead Boiling ranges to limit their mutagenicity indices. The reference does not suggest the addition of paraffinics to reduce mutagenicity of asphalt compositions.
Parent U.S patent application Ser. No. 08/697,385, filed Aug. 23, 1996 (docket number 6505AUS), discloses asphalt compositions containing a solvent refined paraffinic neutral mineral lubricating oil and an optional polymer additive.